Sandberg studied economics at Harvard University in Cambridge, Massachusetts. There she did her undergraduate thesis with economist Lawrence Summers as her adviser. She received her bachelor’s degree in 1991 and was the top student in economics. When Summers became chief economist at the World Bank in Washington, D.C., Sandberg joined him there, and together from 1991 to 1993 they worked on projects that helped developing countries.

Sandberg received a masters master’s in business administration from Harvard in 1995, and from 1995 to 1996, she worked at the management consulting firm McKinsey & Company. Summers became deputy secretary of the Treasury in 1995, and Sandberg joined him at the Treasury Department in Washington, D.C., as his chief of staff in 1996. From the time Summers became Treasury secretary in 1999 until he left the post in 2001, Sandberg was his chief of staff.

In 2001 Sandberg joined the search engine company Google, Inc., as general manager of its business unit, notwithstanding that Google had no business unit at the time. She soon became vice president of global online sales and operations. She was in charge of development of AdWords, which placed text advertisements on search result pages, and of AdSense, which placed relevant advertisements on the Web sites of individuals and companies that contracted with Google. Both AdWords and AdSense helped Google become a profitable company and were responsible for much of Google’s earnings. In 2004 she was put in charge of Google’s for-profit philanthropy arm, Google.org, which focused on the problems of climate change, public health, and poverty.

Sandberg was recruited as Facebook’s first COO in 2008. The social network Facebook had grown enormously since its founding in 2004, and founder Mark Zuckerberg felt that someone more experienced in management (such as Sandberg) was needed to supervise the daily operations of the company. Just as she had at Google, Sandberg created an advertising strategy for Facebook that allowed the company to finally become profitable, and her close partnership with Zuckerberg was seen as a crucial ingredient in Facebook’s success.

Sandberg became an outspoken advocate for women to be more aggressive in seeking success in the business world. She often pointed out that, despite the gains women had achieved through feminism, business executives were still predominately male, and women needed to close “the ambition gap.” She felt that, for women to want to return to work after having children, they should do everything they could to seize interesting and challenging opportunities early in their careers. Sandberg articulated her philosophy in Lean In: Women, Work, and the Will to Lead (2013); the book was published in concert with the launch of Lean In, an education and community-building organization for women in business. Though Sandberg’s advocacy was generally well received, some critics noted that her experience and position were so rarefied and unique as to be irrelevant to the typical working woman.